module: throw error for ESM syntax in explicit commonjs entry

lib/internal/modules/cjs/loader.js

@@ -1751,6 +1751,7 @@ function wrapSafe(filename, content, cjsModuleInstance, format) {
  * @returns {any}
  */
 Module.prototype._compile = function(content, filename, format) {
+  const explicitCommonJS = format === 'commonjs' || format === 'commonjs-typescript';
   if (format === 'commonjs-typescript' || format === 'module-typescript' || format === 'typescript') {
     content = stripTypeScriptModuleTypes(content, filename);
     switch (format) {
@@ -1777,6 +1778,11 @@ Module.prototype._compile = function(content, filename, format) {
     const result = wrapSafe(filename, content, this, format);
     compiledWrapper = result.function;
     if (result.canParseAsESM) {
+      // Throw for ESM syntax in explicitly CommonJS main entry to avoid silent failure.
+      if (explicitCommonJS && this[kIsMainSymbol]) {
+        const pkg = packageJsonReader.getPackageScopeConfig(filename);
+        throw new ERR_REQUIRE_ESM(filename, true, null, pkg?.pjsonPath);
+      }
       format = 'module';
     }
   }

test/es-module/test-esm-syntax-in-cjs-main.js

@@ -0,0 +1,38 @@
+// Flags: --no-warnings
+'use strict';
+
+// Test that running a main entry point with ESM syntax in a "type": "commonjs"
+// package throws an error instead of silently failing with exit code 0.
+// Regression test for https://github.com/nodejs/node/issues/61104
+
+const { spawnPromisified } = require('../common');
+const fixtures = require('../common/fixtures.js');
+const assert = require('node:assert');
+const { execPath } = require('node:process');
+const { describe, it } = require('node:test');
+
+describe('ESM syntax in explicit CommonJS main entry point', { concurrency: !process.env.TEST_PARALLEL }, () => {
+  it('should throw ERR_REQUIRE_ESM when main module has ESM syntax in type:commonjs package', async () => {
+    const mainScript = fixtures.path('es-modules/package-type-commonjs-esm-syntax/esm-script.js');
+    const { code, signal, stderr } = await spawnPromisified(execPath, [mainScript]);
+
+    // Should exit with non-zero exit code
+    assert.strictEqual(code, 1, `Expected exit code 1, got ${code}`);
+    assert.strictEqual(signal, null);
+
+    // Should contain error about ESM in CommonJS context
+    assert.match(stderr, /ERR_REQUIRE_ESM/,
+      'Expected error message to contain ERR_REQUIRE_ESM');
+    assert.match(stderr, /esm-script\.js/,
+      'Expected error message to mention the script filename');
+  });
+
+  it('should include helpful message about package.json type field', async () => {
+    const mainScript = fixtures.path('es-modules/package-type-commonjs-esm-syntax/esm-script.js');
+    const { stderr } = await spawnPromisified(execPath, [mainScript]);
+
+    // Error message should mention the package.json path for helpful debugging
+    assert.match(stderr, /package\.json/,
+      'Expected error message to mention package.json');
+  });
+});

test/fixtures/es-modules/package-type-commonjs-esm-syntax/esm-script.js

@@ -0,0 +1,4 @@
+// This file has ESM syntax but is in a "type": "commonjs" package
+console.log('script STARTED');
+import { version } from 'node:process';
+console.log(version);

test/fixtures/es-modules/package-type-commonjs-esm-syntax/package.json

@@ -0,0 +1,3 @@
+{
+  "type": "commonjs"
+}